'use strict'

const http = require('http')
const fs = require('fs')

function parseBodyHeaders(data) {
  let headers = {}
  let dsplit = data.split('\r\n').filter(p => p.length > 0)

  let ind
  let k
  for (let d of dsplit) {
    ind = d.indexOf(':')

    if (ind <= 0) continue
    
    k = d.substring(0, ind).toLowerCase()

    headers[k] = d.substring(ind+1).trim()

  }

  let cpd = headers['content-disposition']

  //按照; 分割成数组，第一个元素form-data去掉
  let clist = cpd.split('; ').slice(1)

  let name, filename
  
  for (let a of clist) {
    ind = a.indexOf('filename="')
    if (ind >= 0) {
      filename = a.substring(ind+10, a.length-1)
    } else {
      name = a.substring(6, a.length - 1)
    }
  }

  return {
    headers,
    name,
    filename
  }

}

/**
 * 
 * @param {Buffer} bodyData 原始的Body数据
 * @param {Object} reqHeaders reuqest.headers
 */

function parseBody(bodyData, reqHeaders) {
  
  //content-type: multipart/form-data; boundary=-----34294329
  let ctype = reqHeaders['content-type']

  //拿到分界线boundary
  let bdy = ctype.substring( ctype.indexOf('=')+1 )

  //数据中用于分割文件的分界线
  //let bdy = `--${bdy}\r\n`

  let crlf_bdy = `\r\n--${bdy}`

  //从偏移bdy的长度开始查找下一个分界线的位置
  let data_end_index = bodyData.indexOf(crlf_bdy, crlf_bdy.length)

  //body消息数据中header部分的最后索引
  let header_end_index = bodyData.indexOf('\r\n\r\n', crlf_bdy.length)

  let header_data = bodyData.toString('utf8', 
                                  crlf_bdy.length, 
                                  header_end_index);

  //解析body数据中的消息头
  let hd = parseBodyHeaders(header_data)
  
  let fileinfo = {
    start: header_end_index+4,
    end: data_end_index,
  }

  fileinfo.length = fileinfo.end - fileinfo.start

  return {
    name: hd.name,
    filename: hd.filename,
    headers: hd.headers,
    start: fileinfo.start,
    end: fileinfo.end,
    length: fileinfo.length
  }

}

let routerTable = {

  GET: {
    '/upload' : async (request, response) => {
        let stm = fs.createReadStream('./upload.html')
        stm.pipe(response)
        stm.on('end', () => {
          response.end()
        })
    }
  },

  POST: {
    '/upload' : async (request, response) => {

      console.log(request.headers['content-type'])

        let bufferList = []
        let totalLength = 0

        request.on('data', chunk => {
          totalLength += chunk.length
          bufferList.push(chunk)
        })

        let bodyData = null

        request.on('end', () => {
          bodyData = Buffer.concat(bufferList, totalLength)
          bufferList = []

          //解析Body数据
          let body = parseBody(bodyData, request.headers)
          console.log(body)

          response.setHeader('content-type', 
                      'text/plain; charset=utf-8')

          response.end(bodyData)
        })

    }
  }

}

let serv = http.createServer()

serv.on('request', (request, response) => {
  let rm = routerTable[request.method]

  //根据？切割字符串
  let usplit=request.url.split('?');
  let pathname=usplit[0];
  let querystring=usplit[1]||''

  if (!rm || !rm[ pathname ]) {
    response.statusCode = 404
    response.end('page not found')
    return
  }

  rm[ pathname ](request, response)
})


serv.listen(3456)
